Whitened glass in which a light transmittance is reduced by interposing particles having refraction indexes different from each other, and the like in transparent glass to cause light scattering, or by uniformly dispersing opaque fine particles in a predetermined amount from the first, is generally called opalescent glass, Oparine glass, or white glass. The whitened glass has been used as a container, tableware, a building material, and the like in consideration of satisfactory beauty and storage stability.
Here, a white glass composition in the related art typically contains a predetermined amount of fluorine, and a crystal phase of NaF as an opalescent component uniformly dispersed in a glass phase of SiO2 as a main component, thereby obtaining an opalescent color (for example, refer to Patent Document 1).
More specifically, the white glass composition in the related art is a white glass composition that contains 70% by weight to 73% by weight of SiO2 and 4% by weight to 6% by weight of fluorine, and a white glass container is formed using the white glass composition.
On the other hand, a method of manufacturing crystallized glass formed from a glass composition that does not contain fluorine is suggested (for example, refer to Patent Document 2).
More specifically, the method is a method of manufacturing opaque (white) crystallized glass which contains phosphorous. The method includes forming glass by using a glass composition containing a predetermined glass composition in an amount of 90% by weight or more on the basis of the total amount, the predetermined glass composition containing, in terms of % by weight, 45% to 65% of SiO2, 3% to 15% of Al2O3, 10% to 25% of Na2O, 12% to 25% of CaO, and 3% to 8% of P2O5. Then, the glass is gradually cooled, and is subjected to a post-heat treatment at approximately 900° C. to perform crystallization.
Furthermore, the applicant of the invention suggests an opalescent glass composition which does not contain a significant amount of fluorine, which can be safely and easily produced, which has high whiteness, and which can be melted at a low temperature (for example, refer to Patent Document 3).
More specifically, the opalescent glass composition contains 35% by weight to 65% by weight of SiO2, 3.5% by weight to 10% by weight of P2O5, 5.5% by weight to 15% by weight of Al2O3, 3% by weight to 15% by weight of CaO, and the like so as to obtain opalescent glass by only melting a predetermined glass raw material at approximately 1400° C. and performing gradual cooling.